The term “AGM granules” as used herein includes materials capable of absorbing and storing a high amount of liquid compared with the volume thereof. “AGM” is the abbreviation of Absorbent Gelling Materials. These materials are mainly formed by superabsorbent polymers. In the present context the AGM material may be used as granules of different particle size including powder like materials or a mixture of powder material and granules of different particle size or forms (e.g. fibers).
AGM materials of this kind are usually embedded into absorbent pads of melt blown fibers or cellulose fibers (or similar fibrous materials and combinations thereof) or directly deposited onto a non-woven carrier layer. The present invention is applicable to both of these methods. This kind of “absorbent article” may be used for example for manufacturing a diaper, a sanitary towel or even a liquid gathering article of any kind.
Various approaches have been proposed for obtaining AGM granule distribution on a substrate having a predetermined pattern and thickness profile. These approaches include blowing an airborne mixture of AGM granules and fibers through a conduit onto a vacuum drum. Methods of this kind only allow a limited control of the pattern and the distribution of the thickness of the AGM over the surface onto which the AGM is distributed.
Particularly in case of low or no cellulose fiber containing absorbent cores, having AGM granules as the only liquid storage material, AGM granule distribution with accuracy with respect to shape and discreetness is highly important.
In this context it should be mentioned that it is possible to use single or multi piece cores, one layer of AGM or several layers on top of each other overlapping or besides each other. This also allows to use different AGM's in different layers. Thus the possibilities of variation of the achieved product are nearly endless. However, high accuracy of the granule distribution is important.